Recent work in the field of olefin upgrading has resulted in a catalytic process for converting lower olefins to heavier hydrocarbons. Heavy distillate and lubricant range hydrocarbons can be synthesized over ZSM-5 type catalysts at elevated temperature and pressure to provide a product having substantially linear molecular conformations due to the ellipsoidal shape selectivity of certain medium pore catalysts.
Conversion of olefins to gasoline and/or distillate products is disclosed in U.S. Pat. Nos. 3,960,978 and 4,021,502 (Givens, Plank and Rosinski) wherein gaseous olefins in the range of ethylene to pentene, either alone or in admixture with paraffins are converted into an olefinic gasoline blending stock by contacting the olefins with a catalyst bed made up of a ZSM-5 type zeolite. Particular interest is shown in a technique developed by Garwood, et al., as disclosed in European patent application No. 83301391.5, published Sept. 29, 1983. In U.S. Pat. Nos. 4,150,062; 4,211,640 and 4,227,992 Garwood et al disclose the operating conditions for the Mobil Olefin to Gasoline/Distillate (MOGD) process for selective conversion of C.sub.3 + olefins to mainly aliphatic hydrocarbons.
In the process for catalytic conversion of olefins to heavier hydrocarbons by catalytic oligomerization using a medium pore shape selective acid crystalline zeolite, such as ZSM-5 type catalyst, process conditions can be varied to favor the formation of hydrocarbons of varying molecular weight. At moderate temperature and relatively high pressure, the conversion conditions favor C.sub.10 + aliphatic product Lower olefinic feedstocks containing C.sub.2 -C.sub.8 alkenes may be converted; however, the distillate mode conditions do not convert a major fraction of ethylene. A typical reactive feedstock consists essentially of C.sub.3 -C.sub.6 mono-olefins, with varying amounts of nonreactive paraffins and the like being acceptable components.
U.S. Pat. Nos. 4,520,221, 4,568,786 and 4,658,079 to C. S. H. Chen et al., incorporated herein by reference in their entirety, disclose further advances in zeolite catalyzed olefin oligomerization. These patents disclose processes for the preparation of high viscosity index lubricant range hydrocarbons by oligomerization of light olefins using zeolite catalyst such as ZSM-5. The oligomers so produced are essentially linear in structure and contain olefin unsaturation. These unique olefinic oligomers are produced by surface deactivation of the ZSM-5 type catalyst by pretreatment with a surface-neutralizing base.
The formulation of lubricants typically includes an additive package incorporating a variety of chemicals to improve or protect lubricant properties in application specific situations, particularly internal combustion engine and machinery applications. The more commonly used additives include oxidation inhibitors, rust inhibitors, antiwear agents, pour point depressants, detergent-dispersants, viscosity index (VI) improvers, foam inhibitors and the like. This aspect of the lubricant arts is specifically described in Kirk-Othmer "Encyclopedia of Chemical Technology", 3rd edition, Vol. 14, pp 477-526, incorporated herein by reference. The inclusion of additives in lubricants provides a continuing challenge to workers in the field to develop improved additives of increased compatibility with the lubricant and other additives or new additives containing a multifunctional capability that can reduce the number of additives required in the formulation.
The olefinic character of the lower olefin oligomers produced by the aforenoted ZSM-5 catalyzed processes of Chen et al. provides a reactive site to modify those unique oligomers to produce derivatives that can exhibit lube additive properties or improvements in lubricant characteristics or improvement in additive solubility in the base stock. Known derivation reactions of conventional alkenes or olefins include acylation with acyl halides or carboxylic acid anhydrides with Friedel-Crafts type catalysts as described in Advanced Organic Chemistry by E. Earl Royals, pp 381-385, Prentice-Hall, Inc. publisher, and incorporated herein by reference. Using acyl halides as acylating agent results in addition of the acyl moiety and chlorine across the olefinic double bond to produce the corresponding chloroketone which can be dehydrohalogenated to produce an alpha, beta unsaturated ketone. However, it is known that acylation of olefins with carboxylic acid anhydrides using stannic chloride as catalyst produces the alpha, beta unsaturated ketone directly. Acylation of oligomeric alkenes or olefins can, therefore, produce acylated products containing ketone and olefinic unsaturation functionalities which can be used to synthesize further additives or which can exhibit lubricant or additive properties in their own right.
Accordingly, it is an object of the present invention to provide a process for the acylation of olefins or alkenes produced by the zeolite catalyzed oligomerization of lower olefins or alkenes.
It is another object of the present invention to provide novel lubricant additives and lubricants by the acylation of olefin oligomers produced from lower olefins by surface deactivated zeolite catalysts.
Yet another object of the instant invention is to provide novel lubricant mixtures from mineral oil and synthetic lubricants derived from polyalphaolefins and containing lower alkene oligomers containing ketone groups.